Infrared and conductivity measurements show that MClF4 (where M is NO, Rb, or Cs) is ionic in the solid state and in solution, respectively. A square-planar structure (point group D(4h)) is assigned to the ClF4(-) anion in Rb(+) ClF4(-) and Cs(+) ClF4(-). For the ClF4(-) anion in NO(+) ClF4(-) the low-temperature infrared measurement indicates a lower symmetry (at least as low as point group D(2h)). A vacuum line, which will enable running glow-discharge reactions at low temperatures and reduced pressures, was designed and built. Density measurements on the alkali metal difluorochlorates (I) indicate that the X-ray patterns given in the preceding Quarterly Report are probably due to small amounts of alkali metal bifluorides, present as impurities.